Telephone-exchange system.



R". H. MANSON TELEPHONE EXGHANGB'VSYSTEM.

Amman-101w IIQBPPILIAY 25, 1901.

Patented 0011.6, 1908 6 SHEETS-SHEET 1,

R. H. MANSON; TELEPHONE EXCHANGE SYSTEM. Arr-noun: rmm IA! 29, 1907.

900,676. Patented Oct. 6; 190's.

5 SHEBTSa-SHEET 2.

B- H. HANSON. murmur: EXCHANGE sysm.

APPLIOATIOI FILED IA! 20, 1907.

Patented Oct. 6, 1908.

5 SHEETSSHBET 3.

R. H. MANSON. TELEPHONE EXCHANGE SY$TEM.

APPLICATION FILED MAY 29, 1907.

N 9005676! Patented Oct. 6 1908.

5 SHEETS-SHEET 4.

R. H. MANSON.

TLEPHONE EXCHANGE SYSTEM.

AYPLICATION FILED MAY 29, 1907.

Patented Oct. 6, 1908.

5 SHEETS-SHEET 5.

STATES PATENT OFFICE.

RAY H. MANSON, OF ELYRIA, OHIO, ASSIGNOR TO THE DEAN ELECTRIC COMPANY, OF ELYRIA, OHIO, A CORPORATION OF OHIO.

TELEPHONE-EXCHANGE SYSTEM.-

Specification of Letters Patent.

Patented Oct. 8, 1908.

Original application filed. February 1, 1907, Serial No. 355,208. Divided and this application filed May 29, 1907. 7 Serial No. 376,425.

To all whom it may concern? Be it known that I, RAY H. MANSON, a citizen of the United States, residing at Elyria, in the county of Lorain and State of Ohio, have invented certain new and useful Improvements in Telephone-Exchange Systems, of which the following is a specification, reference being had thereinto the accompanying drawing.

My invention relates to telephone exchange systems, and has for its object the production of a ringing circuit for such systems which shall be automatically controlled by the joint act-of the operator and the called subscriber, the former connecting the ringing generator to the called line, and the subscriber disconnecting when he answers the call. In this circuit I employ a thermal type of relay for cutting off the ringing current and commutators for interrupting the flow of generator current so as to give intermittent ringing. These interrupter commutators are so arranged as to provide a ground or shunt path in place of the generator when ringing so that the re lease relay will be operated as soon as the telephone receiver is removed from the switch hook at the called station.

In designing the present circuit I have found it necessary, in order to use a thermal or hot wire relay, to provide a shunt path for line current around'the same, to equalize the effects of the alternating ringing-current and the direct battery current, so that the thermal relay will operate the same when either current is passing throughits Wire.- For this purpose 1 preferably employ a condenser, and I have found that such a condenser will-act automatically as an equalizcr for the difi'erent frequencies employed in harmonic party line signaling so. as to produce a uniform operation of the thermal relay regardless of the character of the current. I

The present application is directed particularly to the feature of equalizing current flow at different frequencies, and is a division of my prior application filed February 1, 1907. Serial Number 355,208.

My invention is illustrated in the accom panying drawings in which Figure 1 is a diagram of a central'ofiice cord circuit and two'subscribers lines adapted'to be connected thereby. Figs. 2 and 3- jack J.

are diagrams of modified substation circuits. Fig. l is a diagram of a modified cord circuit. Fig. 5 is a diagram similar to Fig. 1, showing the calling end of a cord circuit with a multi-generator equipment and connections for harmonic ringing, and

a subscribers party line having harmonicrelay. The contacts onthis key are in par allel. Fig. 8 is a diagram of'a modification of the same key showing cut-ofi' contacts to prevent crossing of two frequencies. Fig. 9 is a side View of akey adapted for use in the circuit shown. Fig. 10 is an end view of said key. I

Referring to the drawings, and particu-- larly to Fig. 1, A and A are two subscrib ers stations each equipped 'withthe'apparatus usually employed in common battery systems. As the line and-other connections and apparatus of these two sub-stations are identical, one description will suflice for both. The line wires 1'2 from. station A pass to the central office, where they terminate upon a jack J and at the contacts of a cut-oil relay N, through which they are nor anally-connected to the line relay hi and the main battery 13 on ground. on the other. line signal lamp m. windings connected on one side "to the ground and on the other side through a wire 3"to the test thimble or ring j c3. the

Of course in the case of a multiple board' the springs j and jand the thimble j will all be duplicated and connected in multiple to the wires 1-2-3'.

For the purpose of interconnecting the lines,'-I provide the usualplugs I and P connected by the cord circuits et-5 and 67. The cord circuit is provided with supervisory relays li -It and li -R controlling the supervisory lamps 1"-r The main bat-I;

one side, 'and to the Relay M controls the 'tery B isbridged across each end of the cordbetween the tip and sleeve-relays, in the; usual manner, these relays therefore serv ing as impedance or choking coils in the. battery supply circuit.

The relay E" has its commutator segments 71 and i For purposes of listening in, and of testing lines to ascertain if they are busy, I provide the usual operators telephone set, with a suitable key for connecting it across the cord conductors 4t-G, and test contacts controlled; by the relay R. For the purpose of ringing the wanted subscriber, I provide the ringing relay R adapted to be set by a key K, so as to open the cord at the contacts r, r, 1' and 1"", and connect the plug 1 through the contacts r 7 to thegenerator wire 8 and the return wire 9. This generator wire extends from the contact i of the commutator or interrupter I to the thermal relay T, and thence to the contact 1' of the ringing relay R wire 9 on the other hand extends from the contact 7' of the ringing relay through the non-inductive resistance 3 to the main battery B and through the ground at g to the point g constituting the common connection of the battery B and the generator G to the The commutator is constantly driven while ringing, and may be maintained constantly in motion, preferably by the same motor which drives the charging and ringing machines. The driving means is immaterial to the present invention, however, and may be anything desirable or available in a particular case. i i

The ringing relay R has its windings connected onone side to the main battery B. On the other side they are connected through wire 11 to the key K and when that is closed to ground, and so to the battery; and also through wire 12 to a selflocking device consisting of the contacts r --r thelatter connected through wire 13 to a contact t in the thermal relay T and thence through its normally closed mate t to ground. Whenever the key K is depressed for a moment, the relay It becomes energized and upon pulling up its armatures locks itself on the following locking circuit, B, R5 12, 1"*,'r, 13, t, t and ground. This circuit, however is controlled by the thermal relay, and the said thermal relay is controlled by the wanted subscriber, having one of its wires included in series with the ringing wire 8, so that when the subscriber answers the relaywill become energized to open its contacts t--t,.breaking the locking circuit, and thereby deenergizing the ringing relay Iii-cutting off the ringing current and restoring the continuity of the cord circuit.. Thethermal relay is constructed and arranged in the following manner; a tension yoke 25 has attached to it but insulated from it the ends of two wires t and 25 The other ends of these wires are attached to points on a pivoted lever 25 these points lying on opposite sides of the pivot tFof the lever. The two wires are maintained under tension by means of the spring t attached The return t.'-Norn1ally the spring rests on the anvil,

and the wires t and z' are maintained under unifori'n tension, so as to keep the lever t in a neutral position. I 11 order to multiply the movement of this lover, I may make it of any length desired.

I have stated that the wire' Sis connected in series with the relay wire i Gel'ierator current passing through the wire 8 must pass therefore through the relay wire also, but the carrying capacity of the wire, and the amount of current which will pass through the line wires and the ringer of the wanted subscriber are so adjusted that such an amount of current will not heat the relay wire sufficiently to destroy the balance of the relay. Of all atmospheric ell'ects the relay obviously remains balanced, because both wiresf and t are exposed to the same changes.

,branch around the wire 15. This capacity constitutes an important feature of my invention, a condenser being employed which will shunt enough of the alternating current from the wiret to prevent the latter being unduly heated. Since I intend that the thermal relay shall be operated both by the battery current and by the ringing current, and since the voltage and consequently the relative amount of current flow through the same resistances is different for the ringing current and for the battery current, it is necessary to provide some means for equalizing the effects of these currents on the thermal relay, and I find 'the condenser or capacity effects this very well. 4 i

The operation of my invention as thus far described will now be understood. Assuming that subscriber A has called for connection with subscriber A, and that the operator has inserted the plug 1 into the answering jaek J, has tested the jaek J of the wanted line and has inserted the plug 1 therein, it remains for her to apply ringing current to the line 12 of subscriber A.

-This she does by depressing the key K for a commutator I is supposed to be rotating whereby its two segments 2', i come into seem c connection alternately with the spring 2'. The segment 2' is shown as the larger or the two, the period of ringing thereby being made longer than the period of rest but this may be varied in any manner desired. The segment i is connected to' the generator G, and the segment i is connected direct to the point a g, whence both branches are connected through the ground to the battery B. The complete ringing circuit while generator is on is as fiollows: G, 2' 2', 8,?" and. t) in parallel, 8, 1*, r tip, 3",1', i l-3,2, 5i, sleeve, r r, y, 9, B, ground, gand backto generator. \Vhen the segment i comes around to the spring z', the 'circuit is the same, except that the generator is cut out and the connection is completed frompoint' g direct'tothe spring z'. This leaves the battery B alone in the circuit, The relay R when pulling up also looked itself over'the following circuit: B, R, 1 2, r", 13,, t, t and ground back to battery. I r

Figs. 2 and 3 show different arrangements of the apparatus at'the subscribers station.

to any particular o'neof these arrangements,

so long as the required basic feature is presented,which isthat with the line in'a condition of disuse, a path of relatively high resistance onlow conductivity is closed for the generator or battery current upon the line; but when the subscriber takes; down his receiver for use, a path of relatively low resistance is closed? In Fig. 1 I have shown the subscribers ringer. permanently bridged across the line with a'eondenser interposed, the resistance of the ringerfeither ohmic oiinductive, or'the capacity of the condenser, or both, being so adjustd that the amount of alternating current. which will pass in ringing is insiifiicient to heat thewire t of the thermic relay T to operate the latter. The

, condenser prevents the passage of direct current. When the subscribers telephoneis in use, aparallel path of relatively low resistance is closed through his'talking set, which permits sufiicient current, either alternating or direct, to pass over the line, to heat the wire t so that, its expansion will unbalance the relay T, tilting the lever t upon its pivot 2 so as liftthe spring t ofi'the anvil t, to open the locking'wire 13therebydepriving the relay R of its ground, and permitting it to retract so as todisconnect the wires 8 and 9 and reconnect-the tip andsleeve of the plug P to the cord conductors 5 and 7 re spectively. I

The arrangement shown in Fig. 2 is the same as that in Fig. 1, except that the ringer and condenser at the subsc ibers station are not permanently bridged but are disconnected when the telephone set is connected. The arrangement shown in Fig. 3 is similar in principle, but has the ringer in a ground tap from the tip side of the line witha suitare not shown in Fig. 5.

will release the relay B and stop the ring- In Fig. 6% have showua'modified arrangem'eut otthe cord c1rcu1t,1n which the wire 9 instead of being connected'direct'ly :to the main ba'tteryB, is connected to a wire 90 controlled by the relay R, and receiving current from battery only when thezsaid relay is energized. This arrangement'has the advantage of leaving the signaling portions of the circuit free from battery connections except -when the calling plug is inserted; in the spring jack; It should be noted that 1 leave the'battery con- ;nected through the resistance to the sleeve It is to be observed that I amnot confined" of theplug. and thence'through the thimble j of the jack to the cut-ofi relay during the ringing, the purpose o f'this being to maintain the cut-elf relay constantly enen gized. .Tliis circuit may be traced as fol lows: B, 9, y, 10, W, sleeve of P, j N and. ground. :Also from P through j to line and. back to j, thence when ringing by way of a, wire 8, i and commutator segment to ground, either" direct or through the gen erator. It should also be noted that the battery current assists the generator current to operate the ithermic relay when the subscriber answers, flowing out over the sleeve side-of the line and back on the tip side and so through the wire 8 and through the gen-- erator to ground, The relay R will be disconnected at the instant the subscriber answers, no matter what the position of the commutator 1 happens to be.

Fig. 5 shows my present invention applied to-a harmonic ringing system, in which I find an equalizing device such as the condenser C to be eminently desirable, if not necessary, in order to secure a uniform action of ringing current at different frequencies upon the thermic relay. The arrangement and connections of the cordcircuit and its bridging relays are preferably the same in this case as those shown in Figs. 1 and 4, but as they 'are immaterial to the particular features important in harmonic ringing, they The plug P and the cord conductors 5 and 7, with the ring; ing relay R its armatures, the battery wire 9, the relay wire 10, thenesistance 1 the @ther'mic relay T, and the connecting wires 8 and 13 are all the same as in the foregoing description. In the present case, however, the wire 11 instead of passing to a single key K, passes to aset of contact springs is, k", k

scriber answers, when the thermic relay T and In in parallel, these springs having anvils k, If, I9 and respectively, all con-' nected in parallel through wire 14 to ground. Instead of a single generator Gr, there are four generators Gr, 3i G and G all connected on one side through the wire 15 to ground; and on the other side connected through the branch wires 16, 17, 18 and 19 to the commutators I, I I and I", respectively; From the contacts of these several commntators' the wires 28, 38, 48 and 58 pass to the anvils 70, I0 76 and .70 of a set of selective ringing buttons whose springs 70 70 is and 70 are connected in parallel to the wire8. In Figs. 9 and 10 I have shown such a set of buttons. Each unit key in this set has a cam roller connected to a push button stem so that when the button is depressed, the pair of springs is, In, etc., with which it is associated, are spread apart against their anvils and are so maintained as long as the button is held down. Each button stem is provided with a me chanical lock and all the buttons are interlocking, the arrangement being such that when pressure is applied to one button, any other buttons which may have been down previously are at once released, and when pressure is removed from the button in use, it retracts through a portion of its path of movementso as to open the ground spring 70, 70 but still maintains the generator springs closed. A convenient 'form of looking mechanism for such a set of keys comprises the common latch shown extending along the side of the button stems, each stem having a pin or pair of pins to engage said latch, these pins being so set that when any key is locked it is held with its generator contacts closed, and its ground contacts open- A form of cam and actuating button for an individual pair of springs is indicated in Fig. I) in connection with the springs 70 and 7a being marked it". It will.be understood that this is merely diagrammatic, but that if individual springs 70, 70 ,70 and 70* areemployed, there should be one of. these double cams for each pair.

It will be observed that in Fig. 5 I show a subscribers line 1'-2 extending to four substations A, A A and A*, the last three of which are indicated by the ringer bridges only. The ringers, at these four stations are tuned so that each will respond to a predetermined frequency .of ringing current only. The four generators G, G G and G, or the equivalent pole changers or irequency changers, are arranged so as to supply' current at corresponding frequencies.

Assuming that it is desi'redjto ring a particular party', as the party at substation A,

on the line l2, the operation is follows:

The line having been tested and found idle,

the plugI is inserted and the selective button associated with the springs I0, I0 is pushed all the way down so as to force both its springs against the anvils 7c and 7c rcspectively. The branch wire 28 leading from the commutator I is thereby connected to the generator Wire 8, and at the same time the ringing relay circuit is closed as follows:

'13, 9, 10, R 11, is, It, 14, ground and back to battery. The ringing relay thereupon pulls A and A* do not respond to current from generator G, but theringer at substation A is effectively actuated, and continues to be so actuated at intervals until the subscriber answers or until the plug P is withdrawn from his jack. n the latter case, and as suming the cord circuit of Fig. 4 to be in use, the relay R is disconnected from the battery, and releases its armatures. In the former case, the rush of current due to the lowering of the resistance at the subscribers station, heats up the wire 6 of the thermic relay T and the latter breaks the locking circuit 13 at the spring 25 as in the previous cases. It should be noted that as soon as the ringing key is set, and pressure is removed therefrom, the spring 70 lifts from the contact b so that the wire 11 is open, and the relay It is thereafter dependent upon its locking circuit13.

In Fig. 6'1 have shown the thermic relay T, the wires 8, 11 and 13 leading to this relay and the keys, the ends of branches 28, 38, 4:8 and 58 and the key springs with their anvils, the latter being arranged in series instead of in parallel, the object of this air rangement being to prevent the connection of more than one generatorto the generator wire 8 at the same time. When any generator spring is moved so as to make contact with its anvil, it is simultaneously disconnected from the following springs, so that it two keys should be simultaneously pressed down, only the lowest one in order would connect its generator to the wire 8.

In Fig 7 I have shown the four springs h, 70 is and 70* replaced by a single master contact k flwhich is closed on its anvil lr when-- ever any of its individual generator springs 70 7a, 70 and k is closed and the button thereof depressed to the fullest extent. 'llus master contacts 70 and is are open. at all other times. A type of key which may be employed in this circuit or any of the other circuits herein described with but slight modification, is shown in Fig. 8 with the series arrangement of Fig. 0. Unless some mechanical means is provided to prevent the depression of two buttons at the'same time, by simultaneous pressure, a cut-ofi' scheme of this kind must be employed if it be. desired to prevent crossing of two frequencies. The ringing circuit being'entirely automatic, if the operatonshould push down two keys at once, two frequencies of ringing current would go to line until one of the subscribers answered. 1

The condenser C in shunt with the wire 25 of the thermic'relay is shown in allof the figures, constituting an essential feature of my invention. Its importance will appear fromv this, that the thermic relay, and in fact any relay to operate satisfactorily ing automatic ringing, must be provided. with some means to equalize the effect thereon of current at different frequencies. A uniform current flow must be maintained, and ,by means of this condenser shunt is maintained in the wire 25 The condenser exhibits a lower resistance to the higher'frequency currents and by properly determining the capacity in advance, the efficiency of the shunt is made to vary approximately with the frequency. Thus, the same effect is produced in the thermic relay with a high frequency current as with a low frequency. In some standard harmonic systems, the frequencies employed range from 16 to 66 cycles and the voltages are graded from 50. for the 16 cycle current to 150 to 175 for the higher frequencies. If no shunt path were provided around the wire 25 of the thermic relay, it would be impossible to adjust the same so as to allow the locking contact t, t to remain closed with high frequency current flowing to line and with the telephone receiver on the hook. The condenser action in equalizing the effect of current at different frequencies is thus the same as in equalizing the alternating and direct current effects, both these effects being combined in harmonic ringing. Y

While I have described my invention herein as applied through the" agency of certain specific forms of apparatus, it is to be understood that these can be varied widely at will. I do not wish to limit myself to any particular type of key, any partieular type of cord or line circuit, or any particular arrangement of automatic or other ringing. The resources of the art are varied and numerous and the field of choice in designing is a broad one.

I contemplate applying my invention to systems and apparatus of various types and all such non-essential changes as are required to make it conform to any given system'l desire to have included within the scope of myclaims. In its broadest aspect the feature of the condenser branch 0" is a ringing shunt or an equalizer, and I am fully aware that other devices may be employed instead of a condenser for a similar purpose. It is to be understood, therefore, that in claiming an equalizer or balancing terconnecting them, a plurality of ringing generators adapted'to supply current of dif' ferent' frequencies, means for selectivel connecting the same through the cord 1' to the line of a wanted subscriber, 'non inductivecontrolling means responsive to the act of the called subscriber to disconnect ling means, whereby it will be equally affected by current at different frequencies, substantially as described.

2. In a harmonic signaling system, means for supplying a plurality of currents at different frequencies, means for connecting the same to a wanted subscribers line, and controlling means therefor, with an equalizing shunt forsaid controlling means, substantially as described.

3.,ln a telephone exchange system, hm monic signaling means comprising a plurality of current sources, a switching device for connecting the same selectively to a wanted subscribers line, and a non-ind uctive controlling device for said switching device together with an equalizing shunt for the controlling device, substantially as described.

4:. In a telephone exchange system, larmonic signaling means comprising a plurality of devices supplying current at dif ferent' frequencies, a plurality of selective keys, a generator wire common to said keys, a ringing relay controlling the genera wire, a non-inductive devicecontrolling the ringing relay, and an equalizing shunt for thejnondnductive device, substantially as described.

ff 5. In a tele hone exchan e system, hari'ality of sources supplying current at different frequencies, a source of direct current, a plurality of comn'iutators, a generator wire common to all the commutators and having branches thereto, a ringing relay controlling the generator wire, a thermal relay connected to the generator wire andv controlling the ringing relay, and a capacity shunt for said thermal relay, adapted to equalize the effect thereon of currents at dille'rent fre quencies, substantially as described.

(3. In a harmonic signaling system for telephone exchanges, a plurality of sources of current at different frequencies, a plurality of selective keys therefor, a master key adapted to be momentarily actuated in the actuation of any selective key, a ringing relay arranged to be energized by said nuister key, a self-locking circuit for said rii scribers line circuits, a (30.(l circuit for in "inonic signaling means con'iprising a plu the same, and an equalizcrfor said controling relay, and a-thermal relay controlling said locking circuit, substantially as described/ 7. In a harmonic signaling system for telephone exchanges, a plurality of sources of current at different frequencies, a plurality of selective keys therefor, a master key adapted to be momentarily actuated in the actuation of any selective key, a ringing relay arranged to be energized by said inaster key, a self-locking circuit for said ring ing relay, and a thermal relay controlling said locking circuit, together with an equalizing shunt for said thermal relay, substantially as described,

Intestimony whereof I afiix my signature in presence of two Witnesses.

RAY H. MANSON.

Witnesses A. J. R BERTS, WV. G. STRONG. 

